1. Field of the Invention
This invention relates to string instruments, such as violins and, more particularly, to a composite string instrument and a method of making a string instrument.
2. Description of the Prior Art
The construction of the violin and other string instruments of its family has changed very little since the 16th century, when well-known artisans such as Stradivari, Guarneri and Amati mastered the craft. Their instruments are considered the best for tone, power, beauty and, of course, investment. Because they are so rare and so expensive, it is not often that a person even gets to hear and see one played. Wooden instruments of this type are a thing of beauty, and also a delicate, fragile, never-can-be-replaced piece of workmanship.
The violin itself comprises a soundbox, a neck, a pegbox, and four strings stretched tightly over the soundbox. The strings attach to a device at the lower end called a tailpiece, extend over a bridge near the center of the soundbox, and continue to the tuning pegs within the pegbox at the upper or distal end of the instrument. When the string is vibrated by plucking or by drawing a bow over it, it induces a vibrational energy through the bridge to the top and bottom plates of the soundbox (hereafter called the "belly" and the "back"). The vibration of these plates enhances and amplifies the vibration initiated at the string, and sound is produced. The belly and back are connected around their perimeter by a sidewall called the rib, and are additionally connected by a column called a sound post.
Because of the tedious and exacting workmanship involved in the making of wooden instruments, there have been numerous attempts to fashion instruments out of synthetic materials over the past few decades. The idea is that with proper tooling, a consistent, easily manufactured instrument might be produced. However, the mass market for such instruments has not been attained for various reasons, such as poor sound quality, inferior looks, or problems involved in the conjunction of both synthetic and natural wood materials together in the same instrument.
In U.S. Pat. No. 3,699,836 (Glasser), a violin is produced using sheets of fiberglass overlaid with a wood paper to simulate the wood look of the natural instrument. This instrument design calls for the belly, back, and rib to be separate pieces, and incorporates a wooden neck and pegbox. The problem with this very typical design for composite instruments is that with all these glue joints, the instrument is more difficult to manufacture. Also, it has much of the fragile nature that the wooden counterparts have. If such an instrument were to be dropped, it would likely break at the glue joints. Elimination of as many of these joints as possible is thus desirable in the manufacture of composite instruments. Also, the preferred medium at this date is graphite fiber within an epoxy resin matrix, and Glasser's claims extend only to fiberglass.
The use of graphite/epoxy materials for musical instruments is taught by U.S. Pat. No. 3,880,040 (Kaman). This invention calls for unidirectional (all strands of fiber going the same direction) graphite layers on both top and bottom faces of a wooden core. The idea is to reduce the thickness of the soundboard by using stiffer materials on the outside of the wooden core. Such an instrument would then still exhibit the pleasant sound derived from a completely wooden instrument, but would also project higher frequencies of vibration because of the thinness of the soundboard.
A disadvantage to such a construction is that over time the wood can delaminate from the graphite/epoxy surfaces. Also, as violin makers are keenly aware, wood has natural variances within from piece to piece, so that a maker could not guarantee consistency of sound from instrument to instrument. Finally, the disadvantage noted above in Glasser's work would apply here, in that the instrument would still be constructed of several pieces that would need to be glued together, and a fragile instrument would still be the result.
In U.S. Pat. No. 4,161,130 (Lieber), a completely synthetic combination of both the lower soundboard and sidewalls (ribs) is found. The invention is for a bass guitar, and is bowl shaped. Because of the complete synthetic nature of the materials, sound control and response to vibration would be more consistent. The disadvantage of this invention is that the neck is bonded or attached separately to the bowl shaped body, and the instrument could easily break at this joint if it were dropped.
Another method of constructing musical instrument soundboxes is taught by U.S. Pat. No. 4,144,793 (Soika and Gene). Rotational molding of plastics involves putting a specific amount or "charge" of plastic powder into a closed cavity mold, and rotating the mold around two axes while concurrently heating the mold to a temperature in which the plastic powder will melt. The mold is then cooled while still rotating, and then disassembled and the part removed. Soika et al proposes making soundboxes for instruments in this manner. The same problem as stated above with this construction is that the neck is bonded secondarily, and is a potential point of breakage. Also, it is well known that acoustic instrument making involves exacting tolerances of the thickness of the soundboards, and rotational molding does not attain these standards, and the acoustic properties are generally not good.
Up to this point, the neck of the instrument had not been addressed in terms of synthetic materials. The neck of the instrument supports the highly tensioned strings, plus the pressure exerted upon the strings by the player of the instrument. Wooden necks must be made of hard wood, a material of sufficient stiffness to prevent the neck from warping or twisting under the high forces exerted by the strings. Since these hardwoods are heavy, this added weight extending outward from the player makes the instrument harder to play and to hold. For this reason, stiffer and lighter weight materials were chosen to make instrument necks, and this is taught by U.S. Pat. No. 4,145,948 (Turner). It should be noted that claim 3 of Turner's patent calls for "said neck including a pegbox section, a neck section and a soundbox section." It is not clear, however, from this claim just how this is to be accomplished. For example, there is no mention of how to reinforce the neck as it joins the soundbox or the pegbox. This reinforcement is necessary to prevent the neck from creeping and rotating upward in the direction that the string tension is pulling it (a very real problem|). Nor does the wording of this claim specifically mention the integral nature of the molding of the instrument. The claim refers to the neck, which is only a small part of the instrument as a whole.
In U.S. Pat. No. 4,836,076 (Bernier), we see a plastic instrument with reinforcement ribs molded to the internal surfaces of the soundboards, and the neck molded integrally with the lower soundboard. The claims call for a stiffening rib running axially along the center of the inside of the lower soundboard, with a plurality of ribs branching off to the sides from this main rib. Although this design displays the integral molding of the neck, ribs and lower soundboard to which this discussion is leading, it must be pointed out that the claims focus on a particular reinforcement rib pattern that is molded in conjunction with the soundboard. This is quite a disadvantage to sound production in quality instruments, in that these major ribs would provide significant damping or muting of the soundboard vibrations. In the violin family, only one such rib is required, and that is found in the "bass bar" located on the underneath side of the belly, or upper soundboard. What is taught by Bernier is not conducive to graphite/epoxy laminates, however. These laminates do not require such reinforcement since they are superior in strength to molded thermoplastics.
Other graphite/epoxy constructions of violins continue along the trend set forth in the '948 patent, Turner, but use unidirectional materials. These are found as sheets laid in specified orientations for the separate soundboards, the belly and the back. U.S. Pat. No. 4,955,274 (Stephens) is one of these. Again, the design calls for the belly, back and rib to be of separate pieces, indicating the necessary glue joints as potential breakage points. Also, the neck and pegbox are indicated by the patent as being of wood, and as such inherit the various problems associated with wooden necks, as taught by Turner. Similar disadvantages appear also in U.S. Pat. No. 4,408,516 (John). Not only is the John violin built in the manner stated above, but there is no differentiation in the physical shape of the belly versus the back. Violin makers for centuries have specific contours ascribed to each of these, and they are significantly different.
Yet another laminate scheme for the belly only is ascribed in U.S. Pat. No. 5,171,926 (Besnainou et al). It is predicted that the same disadvantages associated with the designs of Stephens and John would exist.
A laminate scheme for guitar manufacture is set forth in U.S. Pat. No. 4,969,381 (Decker) in which a combination of woven fabric and unidirectional sheets are used in the soundboards and sidewalls. This combination, along with cotton or silk fabric on the outside, is purported to be a synthetic equivalent of wood for acoustic purposes. This is good in that the combination of high acoustic damping qualities associated with the woven fabric and the low acoustic damping qualities associated with the unidirectional sheets gives a good, resonant tone. Decker's scheme, however, does not provide for variance in the thickness of the back laminate, a detail through which violin makers for many years have painstakingly worked. It has been shown by our research that good tone is accomplished by a laminate stack of varying shapes and sizes in the back portion of the instrument, and that this varies from violin to viola to cello to string bass. Additionally, Decker's design incorporates the same fragile nature disadvantage found above in Stephens' and John's design.
For centuries, the accepted method used by violin makers to keep the neck from rotating up and forward because of the strings' tension has been to place a large wood block inside the soundbox adjacent to the neck. This block would be fitted and glued to the upper and lower soundboards and to the ribs. Guitar manufacturers perform a similar operation. This block would be trimmed as much as possible to keep from damping the soundboard vibrations, but not so much that the neck would rotate over time. Elimination of this block would be of great help to the acoustical properties of the instrument, and a means is found in U.S. Pat. No. 3,974,730 (Adams, Jr.) Whereby this may be done.
The '730 Adams patent discloses a guitar bracing system in which struts arise from each side of the neck at the place where the sides meet the lower soundboard, and angle up to the center of the upper soundboard. Variations within the design include adjustability of the struts, and various locations for these struts. One of the locations is where the struts originate at the base of the neck block, where the block meets the lower soundboard, and then terminates at a cross brace underneath the upper soundboard. While this is good, a more direct bracing would be obtained if the struts could somehow originate at the top of the neck block, and the angle downwards toward the lower soundboard.
In keeping with this idea, U.S. Pat. No. 4,836,077 (Hogue) promotes the idea of embedding a wooden dowel at an angle downwards through the neck and the neck block. This is aimed more as a repair method for neck blocks that were shown to be too weak to prevent neck rotation, than as a standard manufacturing method for new violins. The design still relies on an accurate glue joint between the block and its faces, which still damps the vibrations of the soundboards somewhat.